Human activity pulling the plug on a vital carbon sink

November 16, 2011

(PhysOrg.com) -- Under better conditions coastal ecosystems might be the ace in the hole to mitigate climate change, but human activity is significantly weakening their ability to naturally dampen the impacts of rising CO2 levels according to a new study by Sydney environmental scientists.

In a report being published in Global Change Biology,a research team from the University of Technology, Sydney has recommended that a high priority be placed on protecting and conserving seagrass, salt marsh and mangrove ecosystems.

An analysis of Botany Bay sediments has revealed that since European settlement their composition has changed from largely "blue" carbon sources like seagrasses, mangroves and salt marshes to microalgal sources resulting in an estimated 100-fold loss to their carbon capturing ability.

Lead author of the report, UTS School of the Environment marine ecologist Dr Peter Macreadie, said the research clearly showed the impact was human induced and not part of a natural cycle.

"In other words, we have severely hampered the ability of nature to help reset the planet's thermostat."

"In our study we go back in time, more than 6000 years, to see what effect humans have had on the ability of coastal ecosystems to mitigate climate change through the capture and storage of carbon. We wanted to know what the context was. Have these types of changes occurred in the past or is it unusual? Analysis of the layers of organic matter, or detritus, from two sites within Botany Bay shows that this is an unusual event."

Scientists believe that seagrasses, mangroves and saltmarshes  collectively known as macrophytes  are possibly the most intense carbon sinks on the planet due to their disproportionate ability to capture, and store carbon. However their estuarine habitats are under increasing and continual pressure from human settlement.

"It's something we've seen time and time again. Urbanisation around coastal ecosystems means more runoff and pollutants end up in estuarine habitats which leads to a process of eutrophication which promotes algal growth. Algae can thrive in degraded environments but are much less efficient at sequestering carbon than seagrasses," Dr Macreadie said.

Co-authors, Professor Peter Ralph from the UTS Plant Functional Biology and Climate Change Cluster and Professor of Earth Sciences Greg Skilbeck, said that the study emphasised the important role played by marine and estuarine sediments in sequestering carbon.

"Storage of carbon in sediments is essentially the reverse of fossil fuel use  putting the anthropogenically-used carbon back where it came from in the first place, or at least recognising it is there and not disturbing it," Professor Skilbeck said.

"This is further evidence that these habitats need to be protected from further degradation. We don't know what the risk is of the stored carbon, which has been in that state for possibly thousands of years, being released back into the atmosphere. Seagrass, mangrove and saltmarsh ecosystems should be included in carbon abatement schemes," Professor Ralph said.

An international team of scientists is calling for a targeted global conservation effort to preserve seagrasses and their ecological services for the world’s coastal ecosystems, according to an article published in the ...

The first “State of the Carbon Cycle Report” for North America, released online this week by the U.S. Climate Change Science Program, finds the continent’s carbon budget increasingly overwhelmed by human-caused emissions. ...

The nitrogen cycle plays a major role in seagrass fields. Dutch researcher Arie Vonk studied the nitrogen dynamics of seagrasses in Indonesia. He discovered that the interaction between seagrasses, animals and microorganisms ...

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Don't occupy anything, just consume less. But the breaking windows at the Wall Street is more entertaining than to shut down the TV, close refrigerator and think. BTW Why the Wall Street substitutes the Washington DC? It's a problem of governmental politics, not stock market.

Really it's Occupy everywhere. You know what it is. This is a mass movement that is basically saying "We are here, listen to us". The Tea party was a fake orchestrated movement brought in to Repuglican party for the 2008 midterm elections. Now we are stuck with these dumb-asses. Anyway OWS is real people. It's not orchestrated like tea party.

Oliver Manuel's recent efforts to plaster Physorg.com and other public news sites with his theories and personal URLs are a bit puzzling, as scientists have a variety of publications available to communicate directly to each other in. My best guess is that he is desperately trying to prop up his legacy in light of his arrest in his university office on 7 charges of rape and sodomy based on allegations by 4 of his own children. The charges have been reduced to one count of felony attempted sodomy, not necessarily because of his innocence, but because of the statute of limitations. One can only guess how the recent charges and decades of family strife have affected his ability to reason rationally and to remain objective while defending his unpopular theories.